Host Plant Resistance Breeding

Abstract

Biotic stresses are the damage to plants caused by other living organisms such as bacteria, fungi, nematodes, insects, viruses and viroids. Some of the biotic stresses that devastated the world in the past are the potato blight in Ireland, coffee rust in Brazil, maize leaf blight in the USA. The great Bengal (India) famine in 1943 is also said to be due to crop failure. Annually, it is estimated that almost 15% of global crop yields are lost due to diseases. Since tropics and subtropics favour disease development, the extent of such losses varies with crop and the region. Chemical control was considered as an efficient method; however, the use of pesticide/fungicide dramatically increased, and the overall crop loss has not decreased. This is due to the upsurge of different races of pathogens over a period of time. Breeding for host resistance offers an effective alternative to fungicides/pesticides that can be combined with other management practices as part of an integrated programme. For example, disease-resistant crops perform better with timely planting and harvest and with crop diversification. The dynamics behind host-pathogen interactions is that virulent pathogen populations can arise and attack resistant crop varieties.